"We were coming in from a parking deck at Tulane Medical Center, and a guy in a white shirt started firing at us," Curiel said. "The National Guard [troops], wearing flak jackets, tried to get a bead on this guy. "

The first incident happened around 11:30 a.m. (12:30 p.m. ET) as Curiel and his National Guard escorts headed back to the hospital after dropping off several patients at nearby Tulane Medical Center to be evacuated by helicopter.

Charity shares a helipad with Tulane Medical Center, which is across the street.

They were traveling in a convoy of amphibious vehicles, and Curiel said the vehicle behind him was targeted.

About an hour later, another gunman opened fire at the back of Charity Hospital.